A form in which a company or an individual purchases a server and software at it's own expenses and uses the server and the software has been mainly used. However, in order to reduce TCO (Total Cost of Ownership), cloud computing for using a server and software through the Internet tends to spread.
PTL 1 discloses a technique in which, in a system in which storage apparatuses (local storage apparatus and local file servers) of a plurality of bases (called Edges) and a storage apparatus (a remote storage apparatus and a remote file server) of a data center (called Core) are connected, a file of a base is copied to the data center, the copied file is stubbed and managed in the base, and, when access to the file stubbed in the base occurs, the file is read out from the data center side.
In the system in PTL 1, when a user writes a file in a file system of the local storage apparatus, the local storage apparatus periodically performs replication of the file to the core side. In processing of this replication, time and a period of time when the replication processing can be executed, an amount of data that can be transmitted, and the like are limited in some cases.
The local storage apparatus manages the file as a cache file even after the replication without deleting the file.
Thereafter, when a file system capacity on the Edge side reaches a certain threshold, a cache file with early access date and time is changed to a stub file (stubbed). The stub file is a file that does not have reference to actual data in the Edge and retains reference to actual data in the Core.
In such a state, when access to the stub file occurs from a user, since actual data of the file is not present on the Edge side, processing (recall processing) for downloading the actual data from the Core side to the Edge side is executed.